How can two little words evoke such polarizing emotion as elation or horror? Those two little words can be the happiest thing you’ve heard or possibly the worst.

First a bit of history
Pregnancy is not something that has always been publicly announced. In the Victorian era, pregnancy was typically hidden from public view. Instead of the term “pregnant”, pregnant women were referred to as being in a “delicate condition” or “in the family way”. There were even specially designed maternity corsets to hide pregnancy. Once the pregnancy could not be hidden upper-class women would be confined to home. Announcing the pregnancy was the last thing on their minds.

In addition to possible conflicting social mores, it has not always been easy to detect pregnancy early. Even as late as the 1960s it was not possible to determine pregnancy until later in pregnancy. Pregnancy diagnosis was typically divided into three categories, presumptive, probable and positive evidence of pregnancy. In the 1970s came the sexual revolution and a developing interest in the reproductive sciences. Due to this increase research, a two hour pregnancy test became widely available through doctors offices. By 1976, home pregnancy tests had been approved by the FDA.

Next, a bit of practicality
Today, women may get positive pregnancy test results at home several days before her period is due allowing her to announce her pregnancy as early as 4 weeks pregnant (technically you’ve only been pregnant since conception 2 weeks earlier, but since the number of weeks pregnant are counted from the date of the last menstrual period, it ends up being 4 weeks).

Although they may know earlier, many women do not make the announcement until after 12 weeks, when the risk of miscarriage has declined. Some women want to wait until as late as possible to tell their supervisors due to the perception of pregnancy that still dominate many businesses. Other women share the happy news with everyone they know right away.

Some women use unique ways to tell their husband, family and friends that they are pregnant, such as a wrapped baby shoe with a note, Easter eggs or even a t-shirt.

http://www.elenagreene.com/childbirth.html
http://www.gynob.com/classob.htm
http://www.cola.wright.edu/PublicHistory/rubicon/childbirth.html
A Thin Blue Line: A History of Pregnancy Test Kits. http://history.nih.gov/exhibits/thinblueline/timeline.html#1900